1. Field of the Invention
The present invention relates to an acceleration sensor apparatus for a vehicle which is used with an air bag, a retractor for a seat belt apparatus and the like, provided in the vehicle.
2. Description of the Prior Art
Generally, a vehicle is provided with a variety of measures against an unusually large acceleration imposed thereon. Examples of such measures include deployment of an air bag, and the locking of a retractor of a seat belt apparatus to prevent a webbing from further being released from the retractor. Thus, air bag and retractor apparatuses have an acceleration sensor apparatus to detect accelerations acting on a vehicle that are greater than a predetermined value.
In various apparatuses each having an acceleration sensor apparatus, the acceleration sensor apparatus is mounted at a predetermined angle in relation to a vehicle body. For example, in a seat belt retractor, the acceleration sensor apparatus is mounted on a center pillar of the vehicle body or on a seat cushion at a predetermined angle of installation. Also, in an air bag apparatus, the acceleration sensor apparatus is mounted in a steering panel or an instrument panel at a predetermined angle of installation.
As described above, a conventional acceleration sensor apparatus is mounted at a predetermined angle in relation to a vehicle body. When an acceleration sensor for detecting an acceleration in a predetermined direction is mounted in a movable portion of a vehicle, for example, in a retractor mounted to a seatback of a reclining seat, the angle of the acceleration sensor may vary in some cases. That is, when an occupant tilts the seatback to adjust his/her sitting posture, the orientation of the acceleration sensor apparatus of the retractor alters, resulting in a failure to detect an acceleration in a predetermined direction. As a result, an acceleration in a wrong direction will be detected.
Further, a retractor may be required to be locked to thereby prevent a webbing from further being released from the retractor when the vehicle body is tilted more than a predetermined angle.